Question

A mixture of 40 liters of milk and water contains 10% water. how much water should be added to this so that water may be 20% in the new mixture?

Answer 1

Find percentage of milk:

100 - 10 = 90%

Find the amount of milk:

90% of milk = 0.9 x 40 = 36 liters

Find the amount of water:

40 - 36 = 4 liters

Find amount of water so that it make it 20% of the mixture:

100 - 20 = 80%

80% = 36 liters

1% = 36 ÷ 80 = 9/20 liters

20% = 9/20 x 100 = 9 liters

Find amount of water to add:

9 - 4 = 5 liters

Answer: 5 liters of water is needed to add to the mixture.